So I'm guessing your value has changed - now has punctuation characters (no longer 00098889) in a string.
What you're doing is heading in the right direction, but that code snippet is a bit fragile - as it can't handle gracefully a message with more than none ':' or ','
If this is indeed what your incoming message looks like - read up on char pointers (char*) which will make stuffing your array cleaner.
Also Read up on serial receive - as there are pitfalls when the data is interrupted, or not as expected - in which case your code will get into an unknown state and miss characters or crash.
Final tip.
When posting code for discussion, please post the whole sketch - so we can see what's supposed to be happening - and test it for ourselves if necessary